Experimental study of convection in a model Czochralski crucible using liquid crystal thermography

Abstract

Steady state temperature distribution in a model Czochralski crucible has been mapped by liquid crystal thermography (LCT). The crucible is a water-filled glass beaker. Water is used as the test fluid because of ease of experimentation, as well as the availability of correct thermo-physical properties. In addition, the Prandtl number of water matches those of molten oxides. A copper cylinder whose diameter is smaller than that of the beaker is placed centrally at the water surface. Convection patterns are set up by applying constant temperature difference between the crucible wall and the cylinder surface, in the temperature range of the liquid crystals. The cylinder is given a fixed rotation, thus creating mixed convection conditions in the test fluid. The LCT images recorded in the present study clearly reveal convective rolls, and the interaction of buoyancy-driven convection in the crucible with cylinder rotation. The resulting temperature distributions match numerical simulation quite well. The pure buoyancy and pure rotation experiments result in axisymmetric temperature fields, while in mixed convection, the field is unsteady and three dimensional.

Stereoscopic Digital Particle Image Velocimetry and Digital Particle Image Thermometry analysis of the mixed convection phenomena in the system similar to the Czochralski method of single crystal production

“…In the presented paper all above quantities were calculated separately for SDPIV and DPIT measurements (table 2). Experimental parameters chosen for analysis shows good agreement with the literature data [5][6], [9], [13].…”

“…Later on, Mukherjee et al [8] have used liquid crystals to study the influcence of crucible and crystal rotation on the temperature distribution in the Czochralski crucible. TLC measurement technique was also used by Banerjee et al [9] to investigate the impact of temperature difference and crystal rotation rate on the system stability. Aleksic et al [10] extended those analysis by measuring with DPIT and 2D PIV techniques, the fluid velocity and temperature distribution inside the Czochralski crucible for natural convection and crystal rotation case.…”

Simultaneous imaging techniques for temperature and velocity fields in thermal fluid flows

“…The color of liquid crystal changes from red at low temperatures to green, blue and violet at high temperatures, when they are illuminated by white light. This method can be extended to the simultaneous measurement of temperature and planar velocity field combining with the particle image velocimetry (PIV) (Hiller and Kowalewski, 1989;Gluckman et al, 1993;Kimura et al, 1998;Fujisawa and Funatani, 2000;Park et al, 2001;Banerjee, J. et al, 2006).…”

Visualization of turbulence structure in unsteady non-penetrative thermal convection using liquid crystal thermometry and stereo velocimetry

“…In recent years, the thermal turbulence has been studied using visualization techniques (Dabiri and Gharib, 1996;Funatani and Fujisawa, 2002;Banerjee et al, 2006;Inagaki et al, 2006). The three-dimensional temperature and velocity field in Rayleigh-Bernard convection is measured using scanning liquid-crystal thermometry and a stereo velocimetry (Fujisawa et al, 2005).…”